During the passage of paper through an offset printing press the paper may develop "crumples" or "wrinkles" whereby an uneven spot results which must be absorbed by the cylinder blanket. As a rule a "crumple" or any other uneveness in the paper or between the printing rollers causes a lasting impression upon or in the cylinder blanket, particularly in the outermost or printing ply of a composite or multi-ply printing blanket as a result of which the printing quality is greatly reduced during further printing operations. In many cases there is no other recourse but to replace the entire cylinder printing blanket by a new one which results in relatively high replacement costs.
In accordance with the present invention it was found that the disadvantage latter two noted and others could be avoided by constructing instead of a conventional cylinder blanket a composite cylinder blanket formed of two blankets or bodies, namely, a multi-ply printing blanket which overlies a multi-ply supporting blanket with the plys being immovably adhered to one another but with the blankets being in their totality shiftable or slidable relative to one another when carried by a conventional printing cylinder.
An attempt at the latter may be found, for example, in German Pat. No. 1,279,041 and U.S. Pat. No. 3,045,595. However, in such conventional printing blankets which are constructed of several layers including textile layers, the conventional blankets were easily too strongly plastically deformed or did not resume their original shape sufficiently quickly so that they were crumpled again or recrumpled in the case of renewed pressure during a cylinder printing operation. Furthermore, in keeping with the conventional thought and opinion such conventional blankets generally include soft textured or surfaced cloth which resulted in the fact that the "crumple" impressions lasted longer in the backing or filling blanket which in turn resulted in deformation of the overlying printing blanket.